Glass Eyes That See

[Music] hello there welcome to the moody Institute of science within these halls we attempt to answer some of the mysteries of creation in the realm of physics chemistry biology and many related Sciences we have been permitted to view the handiwork of the Creator we have so very many things to show you and so little time in which to do it we shall have to leave many things for another time but for now let's investigate some of the facts concerning life a very illuminating subject by the way and in some instances rather amusing for example I wonder how many of you realize the lights in your home are going on and off a hundred and twenty times a second your eyes cannot see the separate flashes but I have a glass eye that can can you tell which one it is if this one we call it a photocell an electric eye that can see a great many things the human eye misses altogether I have a photocell identical to this one mounted inside this instrument it's connected to the amplifier and whatever the photocell sees will be converted into sound and you'll hear it on a loudspeaker let's take a look at this ordinary household lamp [Music] what you were hearing was the light going on and off a hundred and twenty times a second that's because we have 60 cycle alternating current the flashlight does not produce any sound because it has a battery direct current source of energy that keeps the tiny filament incandescent all the time whenever I interrupt a beam by some mechanical means sound is heard listen or with a comb I can saw the light into little pieces what you were hearing was like sawdust this comb happens to have tenor teeth and bass teeth here are the tenor key and the bass now anyone can see that by going fast enough for the high notes and slow enough for the low notes I should be able to play a little tune would you like to hear me play Yankee Doodle on the comb I was afraid you would I can't do it maybe this will help it's a metal disc where the number of holes carefully arranged in its surface as I spin the disc and shine the light in back of it the light is interrupted in a precise pattern [Music] [Music] here is another light source that is apparently on all the time actually it's off more than it is on at this moment it is flashing 3,500 times per minute the duration of each flash is only 50 millionth of a second that means if I were to leave the lamp on for five minutes it would only be illuminated a total of one second the dial on the side permits me to control the flashing rate of the light you will notice a variation in sound as I vary the speed [Music] why does the I receive the impression that the light is on all the time and yet that photocell never misses a flicker it's because of a phenomena called persistence of vision that is an image received on the retina of the eye as retained for approximately a tenth of a second before it fades away one flash every tenth second is sufficient to keep the retina activated all the time how does the photocell function in simplest terms it's this according to one of the theories light is composed of particles inconceivably small traveling at tremendous velocities when they strike the photocell a few electrons are knocked off producing a feeble current of electricity that tiny current may be amplified to perform a number of interesting functions perhaps this will give us a more graphic concept of the energy involved in light this is a glass envelope from which the air has been highly exhausted the tiny paddle wheel inside is mounted on a jeweled pivot I'm holding the instrument on its side to prevent the paddle wheel from turning in an upright position if silvered vanes are free to rotate as light illuminating the laboratory strikes them the things we're learning today about the particles that compose the world in which we lived are causing men of science to stand in awe of the Creator who brought them into existence as dr. Arthur H Compton Nobel Prize winner in the field of physics stated concerning the tiny world of the atom a God who can control a universe like that is mighty beyond comprehension now the photocell has many practical applications from opening closing doors to counting and starting beams this is not exactly on the practical side but at least it demonstrates what we're talking about now anyone can light a lamp for the match but with only two tons of equipment we can put the lights out with a match this might be what you would call blowing the lights off this instrument accomplishes the seemingly impossible it translates music the human voice any sound into a modulated beam of light it employs another brainchild of this fabulous 20th century a facsimile tube originally designed for the reproduction of photographs by radio it has a tiny incandescent crater in its heart that may be turned off and on over a million times a minute that spot of light is projecting the music of an entire Orchestra right into your eye naturally you cannot see or hear anything but let's let the glass eye take a look the music you now hear is being picked up from a tape recorder modulated on a beam of light projected across the room at 186,000 miles per second into the photoelectric cell and immediately reconverted into sound that beam of light is in front of me now but I can either see it taste it touch it or feel it but look my hand blocks the light and stops the music at every position between these two instruments that invisible beam of light is carrying a message of music but you like a handful of music any dense object will produce the same effect somehow I could never get it through my head now then instead of a tape recorder I would use a microphone and project my voice across the room on a beam of light I understand the military has a similar instrument for secret communication between ships at sea only those directly on the beam of light can hear what is being said the important thing is this at this very moment there is an invisible intangible link between my voice and your ear if I block that link you will not hear my voice 1 2 5 6 9 10 well that's as far as I can count but by this time you have the idea seriously perhaps some do not fully understand how it was possible for me to project my voice across the room or nothing more than a soundless beam of light well to be perfectly frank about it there are things about it that I don't understand there are principles involved that no one understands for example we know how sound is propagated through space but how does light go sound travels approximately 1,100 feet per second at sea level but light travels a hundred and eighty six thousand miles per second but how by what means through what medium no one knows dr. Willis our Whitney former director of research at General Electric was asked for a definition of the propagation of light he said gentlemen to the best of my knowledge light goes by the will of God he went on to say no one today can give a more precise answer we have the muscular theory the wave theory and now the quantum theory but at best they are but educated guesses mystery well this old universe is fairly bursting with unanswered questions you know one of the interesting things for me to discover among men of science is that the great question of our day is not is there a god but how is it possible that man can communicate with the Creator on a beam of light I'm afraid I don't know I can tell you no better than how life goes but I know it's real men in all walks of life have demonstrated humble men of science have been men oppressed Lord Kelvin Herschel Bacon the prince of them all Sir Isaac Newton who formulated the laws of motion invented calculus discovered the law of inverse squares himself declared all my discoveries have been made an answer to prayer mystery of mystery man communicating with his maker a personal God that yet today counsels his sons in the words of John this is the message we have heard of him and declare unto you that God is light and in him is no darkness at all if we walk in the light as he is in the light we have fellowship one with another and the blood of Jesus Christ His Son cleanseth us from all sin [Music]